The present invention relates to the construction of an electronic calculator and more particularly to the construction of a casing of an electronic calculator.
A substrate or a printed board is unavoidably required in the conventional electronic calculator. Key contact patterns and wiring patterns were formed on the substrate and the electronic elements such as an LSI including a computation circuit and a display unit are mounted on the substrate to establish electrical connection with the wiring patterns formed on the substrate. The substrate carrying the electronic elements thereon is disposed in and supported by a casing of the electronic calculator.
The substrate is considerably thick since it must endure pressure caused by the key depression. This results in an electronic calculator which is considerably thick even though the necessary electronic elements are all mounted on a single substrate.
Accordingly, an object of the present invention is to provide an electronic calculator of minimum thickness.
Another object of the present invention is to provide a casing of an electronic calculator suitable for minimizing the thickness of the electronic calculator.
Still another object of the present invention is to provide a key input device suitable for minimizing the thickness of an electronic calculator.
Yet another object of the present invention is to provide an electronic calculator having no substrate or printed board.
Other objects and further scope of applicability of the present invention will become apparent form the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objectives, pursuant to one embodiment of the present invention, wiring patterns and key contact patterns are formed directly on an inner surface of a casing of an electronic calculator. Electronic elements are mounted on the inner surface of the casing to establish electrical connection with the wiring patterns formed on the inner surface of the casing. The electronic calculator becomes thin since the substrate or a printed board can be eliminated.